RE: ESM P51b Engine Help
The bigger the motor, the bigger the prop you can use for closer to scale.....but...also the more fuel you'll use. The 150 is much better on fuel then the 180 and can still spin a decent size prop. I have a 150 in a CMP Corsair with a 16x8 3 blade prop. Tank size is 18oz, but even after 10 mins, it hasnt even used half a tank. On the other hand, my ESM me109e with the 180 and same prop, it uses up 3/4 worth of the tank and can fly 9 mins....same size fuel tank.
The 125 is fine, but, its gonna be somewhat marginal on the p-51b. It'll fly, but it wont be a lot fun. I had a 125 in my Kyosho 71" Spitfire and it flew great...plane weighed 11 pounds. I took it out to use in a TF 60 size P-51 and put a 91 in the spitfire...and now it flies, but cant even do a loop without diving first. So...the esm p-51b will come out weighing 14 pounds or more......the 125 wont be optimal...better suited for an 11 pound TF 60 p-51